Small communication cells (radio cells), for example, femtocells or picocells, allow mobile-network providers to extend the network and to provide better coverage and higher data rates in a cost efficient manner. Such a small cell is an inexpensive base station due to low-power consumption and reduced signal strength. These cells utilize commercial cellular communication standards and common licensed transmission spectra. To a mobile station, for example, a mobile phone, a smart phone or tablet computer, a small cell appears indistinguishable from a traditional base station, as they all have the usual overhead channels, signalization and are capable of in-band handoffs.
By integrating a small cell into a vehicle, all 3G/4G/5G-equipped devices used inside the vehicle can be connected to a mobile-network without any detractions by the vehicle environment. Such detractions occur, for example, by the metallic frame of the vehicle and/or by thermally insulating films applied to the windows of the vehicle.
The architecture of an in-vehicle small cell is described in US 2007/0155421 A1, EP 2 501 200 A1, US 2011/0217947 A1 and DE 10 2012 208 641 A1, but these documents do not describe how to integrate a moving small cell to a mobile communications network in a seamless, stable manner without distortions.
DE 10 2010 028 859 A1 proposes a small cell management by using route guidance information. A similar approach is disclosed in DE 10 2011 007 755 A1.
In contrast to conventional and widely used small cells, which are connected to the backhaul of the network by wire, for example, via DSL, the in-vehicle small cell must be connected by a wireless backhaul link. In most significant cases, this link is established via the base station itself. Accounting for the movement of an in-vehicle small cell is not straightforward and requires additional mobility features that are currently not supported by a mobile-network architecture. For example, since a conventional small cell is installed at a fixed location, in order to enable a seamless handover (from base station to small cell or between small cells), the small cell must be part of the network configuration, such as location areas or a “neighborhood cell list”.
Another issue is that, when the vehicle is moving the wireless backhaul link of an in-vehicle small cell can vary due to radio/data channel transmission conditions and areal coverage.
Yet another issue is that the in-vehicle small cell must work across country borders, which requires specific roaming and re-provisioning mechanisms for the desired services.
Seamless mobility between macro cells/base stations and an in-vehicle small cell, and good connectivity when the vehicle moves, are essential components for a good user experience. Both can be accomplished by a well configured in-vehicle small cell in combination with a in-vehicle WiFi-hot-spot only, according to the present invention (FIG. 1).